The objective of this proposal is to establish the Statistical and Data Coordinating Center for the multicenter randomized clinical trial of prophylactic amiodarone or implantable defibrillator therapy vs. Conventional heart failure therapy in patients with Class II or Class III congestive heart failure (CHF) and an ejection fraction less than or equal to 35%. Qualifying patents (n=2,500) will be randomized in equal proportions to three treatments: conventional CHF therapy and placebo (control arm); conventional therapy combined with the use of amiodarone; and conventional therapy combined with a single lead, pectoral ICD that can be inserted on an outpatient basis. After discharge, all patients will be followed via clinic visits at 1 week, 4 weeks, 3 months, and every 3 months thereafter. Patients will be recruited over a period of 2.5 years, with a subsequent minimum follow-up of 2.5 years. The primary endpoint of the trial is all-cause mortality. Secondary endpoints include: 1) cardiac mortality and arrhythmic mortality; 2) ventricular tachycardia/fibrillation and bradyarrhythmias assessed via the ICD memory log; 3) morbidity; 4) quality of life; and 5) cost of care and cost effectiveness. In collaboration with the Clinical Coordinating Center (CCC) and the Economics and Quality of Life Center, the Data Coordinating Center will perform the following major functions: 1) participate in all phases of study planning; 2) coordinate the preparation of data collection forms; 3) prepare a manual of operations; 4) provide training/guidance in data collection procedures; 5) coordinate the randomization of patients; 6) organize the flow and management of all patient data; 7) establish high standards of quality control for data management; 8) perform on-site monitoring of completed data forms; 9) prepare regular status reports for the CCC and for all study committees; 10) dispense payments to clinical sites for enrolling and following patients; 11) perform appropriate statistical analyses of study data; and 12) participate in the preparation of study publications. Noteworthy features of this proposal include: a detailed assessment of sample size requirements; telephone randomization of patients; double data entry; on-site audits of data; economical and efficient computer hardware and software; state-of-the-art methods of data analysis; and an experienced team of investigators. Through the services it provides, the Data Coordinating Center will be a vital resource in the execution of this clinical trial.